1. Field of the Invention
This invention relates generally to new and useful improvements in area watering systems wherein a tower supported water pipe travels in a circular path about a central supply point, and particularly to an automatic forward bow alignment system for keeping the towers of such a watering system in proper position with respect to one another.
2. Description of the Prior Art
It is known in the irrigation industry that water-turbine drive pivots must never be operated with a reverse bow, because such reverse bow will cause the pipe connecting together the towers of the device to be placed in compression along the forward, or leading, side thereof, which compression will subsequently cause damage to the machine. Thus, it is desirable to operate the pivot with a slight forward bow, because such a bow will cause the main line, or pipe, to be operated while in tension along the forward, or leading, side thereof. Pivot irrigators have more strength in the tension mode than in the compression mode, and have a history of bending main line pipe any time that they are operated in the compression mode. If the pivot is reversible, the forward bow must be established immediately in the opposite direction when the device is reversed.
U.S. Pat. Nos. 3,628,729, issued Dec. 21, 1971 to J. R. Thomas, and 3,599,664, issued Aug. 17, 1971 to K. W. Hotchkiss et al, disclose pivot irrigators in which the towers are controlled so as not to get ahead of a line radiating from a pivot of the apparatus, while U.S. Pat. No. 3,780,947, issued Dec. 25, 1973 to M. H. Ririe et al, discloses a pivot irrigator alignment control which includes the use of a wind vane arranged for compensating for the effect of wind on a control wire which selectively opens and closes switches regulating movement of the apparatus.